This invention concerns boat lifts and more particularly concerns automatic levellers for pneumatically operated boat lifts.
The use of pneumatically operated boat lifts to dry-dock boats during temporary periods of non-use is a fairly common practice. All such lifts presently known suffer from some basic inadequacies. Most of them require some sort of support structure on both sides of the lift such as a dock or pier or the like. This double-dock structural requirement increases the cost and complexity of the overall boat lift project. Many lifts require the use of dock mounted control boxes which are subject to vandalism and use up valuable dock space. Other lifts incorporate no means whatsoever for levelling the lift during the lifting and lowering processes. No known lift provides a pneumatic system for levelling itself in automatic response to unacceptable degrees of list during the lifting and lowering processes. Consequently, changes in wind and wave conditions, weight distribution imbalances in either the boat or the lift or unequal rates of pneumatic flow in the lift system can result in damage to, or capsizing of, the boat and even the lift during these processes.
It is, therefore, an object of this invention to provide a boat lift and leveller which can be used without the requirement for support on both sides of the lift. Another object of the invention is to provide a boat lift and leveler which employ controls mounted on the lift rather than on the dock. It is further an object of this invention to provide a boat lift which incorporates an automatic self-levelling system to maintain the stability of the lift during the lifting and levelling processes. And it is an object of this invention to provide a boat lift and leveler which incorporates an automatic self-leveling system which maintains the stability of the lift during storage.